Tire sensor

ABSTRACT

A tire monitoring device for monitoring various tire conditions of a tubeless tire mounted on a vehicle wheel having a recessed portion of the wheel and a wheel rim  5  defining the recessed portion, including a composite wheel having at least one wire free transmitter and a receiver incorporated into and embedded into the surface of the composite wheel in the recessed portions of the wheel. The transmitter and receiver will monitor, transmit and receive signals about the tire condition, including tire pressure and temperature. Also included is an embedded antenna permanently incorporated into the recessed portion of 10 the composite wheel, such that the antenna becomes a part of the wheel, with an antenna winding length of from about 0.5 to about 5.0 meters long. Other embodiments include the use of a toroidal antenna in the recessed portion of the wheel.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a 371 of PCT/US02/20531 filed on Jun. 25, 2002,which claims the benefit of U.S. Provisional Application No. 60/300,874filed on Jun. 25, 2001.

BACKGROUND OF THE INVENTION

Recently, low tire pressure has become an issue in the news because manytravelers have died from rollover accidents due to low tire pressure.Automakers have determined that it would be a safety initiative to havea dash read-out that would tell the driver of a vehicle when they havelow tire pressure. Therefore, a new industry is coming forward to meetthe demand of providing low pressure tire sensors to the automakers. Infact, in a white paper by Goodyear Tire & Rubber Company, and aspublished by the Society of Automotive Engineers, 250,000 accidents ayear are a result of under-inflated tires. The cost in repairs due toaccidents pales in comparison to the toll in human suffering due toinjuries and even deaths that could possibly have been avoided had thedriver been alerted of a potential tire problem.

Apart from the need to reduce the number of accidents and resultinginjuries, there are major ecological implications for this technology.For instance, if a tire is under inflated by just 5 psi, it increasesfuel consumption by 10%. Simplistically, in England alone, some 200,000gallons of fuel per day could be conserved with proper tire pressure.This equals 73 million gallons per annum, a savings into the millions ofdollars with considerable environmental benefits.

Many vehicles have had one or more tires deflate or go completely flat,sometimes even violently as in the case of a blowout while traveling. Attimes the driver is not immediately aware of the situation and maycontinue to drive on the remaining tires, dragging them on the pavementand causing them to become damaged as well. A blowout at high speeds cancause extensive damage if it goes undetected. The tire disintegrates anddebris can damage the vehicle or other vehicles driving on the remnantsof the now fragmented tire, steel belt, and bead wire. In the case ofdual rear tires on a four-wheel axle, the size and subsequent loudernoise and vibration experienced by the driver may cause this conditionto go unnoticed, even resulting in the tire or even the vehicle catchingfire.

Another concern about loss of tire pressure or low tire pressure is thatit affects the load carrying capability, along with steering andbreaking, affecting the overall control of the vehicle. This and theoften disproportioned weight or center of gravity has lead to numerousroll-over accidents, resulting in an extensive loss of life, innumerableinjuries, and devastating economic consequences for the drivers,passengers, insurance companies, vehicle manufacturers, and tiremanufactures alike.

In an attempt to help to prevent further accidents of this nature, onNov. 1, 2000, the United States Congress and former President Clintonpassed and signed into law House Bill H.R. 5154 entitled theTransportation Recall Enhancement, Accountability, and Documentation(“TREAD”) Act. Section 13 of this new law requires that within threeyears of the final rule making proceedings, every passenger car,multipurpose passenger vehicle, and truck with a gross vehicle weightrating of 10,000 pounds or less will be required to have a warningsystem installed in the vehicle to indicate to the operator when a tireis significantly under inflated. It is expected that other countrieswill follow suit.

Many inventors have been working on this problem long before legislationmandated an attempted solution. Various electronic devises are found inthe art including several examples of tire pressure monitors and alarmsystems. These are typically fastened to the rim of the wheel andrequired that a hole be drilled through the wheel, or a monitor devicebe strapped or banded to a wheel in order to detect changes in tirepressure or temperature and relay the information to a receiving devisethat then alerts the driver.

Sensors based on Surface Acoustic Wave (SAW) technology have beenpreferred by the original equipment manufactures (OEM) due to theaffordability and availability of materials that can be utilized tocreate a substrate that has the appropriate properties for sendingmechanical, or acoustic waves as the sensing mechanism. These sensorsutilize piezoelectric material to generate the acoustic wave bygenerating an oscillating electric field thereby creating a mechanicalwave, which propagates through the substrate, and then is converted backto an electric field by way of a signal for measurement. The deviseneeds no batteries, thereby avoiding any disposal problems or batteryfailure during operations. SAW devises are highly sensitive, veryeconomical, and very tiny. Many manufacturers of this type of sensorprefer the placement of the sensor itself behind the air valve of atire, using the brass stem as an antenna for transmitting the signal.

In the prior art, there are several examples of tire pressure monitorsand alarm systems. These are typically fastened to the rim of the wheeland require that a hole be drilled through the wheel or attached throughsome sort of banding. See U.S. Pat. No. 4,954,677 or Alberter, et al.;U.S. Pat. No. 4,894,639 of Schmierer; U.S. Pat. No. 4,866,982 of Gault;U.S. Pat. No. 4,768,375 of Echardt, et al.; U.S. Pat. No. 6,378,360 ofBartels; U.S. Pat. No. 6,278,361 of Magiawala; U.S. Pat. No. 5,717,135of Fiorietta; and U.S. Pat. No. 4,784,993 of Lothar, et al. Thesesystems include a transducer of some sort that converts the pressure toa signal for communicating the pressure to a remote display.

The disadvantage to this valve stem antenna design is that it requiressome sort of modification of the wheel rim or valve stem, oftenrequiring holes drilled in the wheel to receive the transducers, therebycausing undue stress on the wheel, retrofitting existing wheels, andraising legitimate safety concerns. Additionally, the attachments canvibrate loose causing sensitive instruments to fail transmitting theirsignal accurately to the monitor located in the cockpit of the vehicle.

The problem of connecting the transducer to a monitor has been solved inpart by radio frequency communications. As shown in U.S. Pat. No.4,890,090 of Ballyns, a pressure transducer is coupled to a radiofrequency transmitter that is mounted within the tire and secured to thewheel rim. Although it has the advantage of wireless communication ofthe pressure to a remotely placed monitor, it suffers from the samedisadvantages of the rim and valve stem mounted sensors in that they aredifficult to install and may become easily damaged and thereby prove tobe unreliable.

To avoid this communication problem, it is possible to indirectlymonitor the condition of the tire using tire rotation sensors like thoseinstalled as original equipment on vehicles with anti-lock braking andsome all-wheel drive systems. To detect a deflating tire, these sensorsare monitored for abnormal changes in rotation speeds of the tireindicating deflation. Doing so requires sophisticated sensors, dataprocessing equipment and algorithms, and a vehicle originally equippedwith this advanced and expensive technology. Although it is asophisticated approach, it is not feasible for most vehicles such asbuses, trucks and motor homes currently being manufactured.

Despite previous substantial efforts to improve the safety of tires,current tire pressure monitoring systems continue to be expensive andelaborate; they require substantial modification to existing wheels andto the car for their use; and they offer methods having little to nofeasibility for retrofitting the millions of ordinary wheels that are inuse and will continue to be manufactured and used.

The current invention discloses several new approaches to monitoringtire pressure and temperature in tubeless tires. Either a new type ofantenna may be used, or the entire package of the sensing device and theelectronic circuitry, which includes the transmitter and an antenna, canbe incorporated into a composite wheel rim during manufacturing. Thesensor and subsequent electronics are in a sealed housing to protect thecomponents from physical damage from flat tire lubricants, tiresealants, and the elements. The housing is embedded in the compositerecessed rim portion of the wheel so as to be affected by the changes inpressure and temperature, without degrading the accuracy of the signalthrough the variations of vibration experienced by other sensor devises.The composite materials lend themselves well to conductivity and will inno way impede the RF signal sent by the SAW devise to the receiver.

A composite wheel is under development by several of the wheelmanufacturers currently supplying original equipment to the automotive,truck, agricultural, utility, and RV markets. These wheels are strongerthan conventional steel wheels, and much lighter. By significantlyreducing the weight of the wheel, fuel economy is greatly enhanced. Thelighter wheels are much easier to store, ship, mount, and manuallyhandle than their steel counterparts. The cost of these composites iscomparable as well with traditional steel wheels, but require lessenergy to produce.

The sensor devise itself may be one of many described herein and is notlimited to the sensors listed, as this technology is rapidly developingand the most ideal sensing device has not yet been determined. Suitablesensors which may be incorporated herein by reference may include U.S.Pat. No. 4,954,677 of Alberter, et al.; U.S. Pat. No. 4,894,639 ofSchmierer; U.S. Pat. No. 4,866,982 of Gault; U.S. Pat. No. 4,768,375 ofEchardt, et al.; U.S. Pat. No. 6,378,360 of Bartels; U.S. Pat. No.6,278,361 of Magiawala; U.S. Pat. No. 5,717,135 of Fiorietta; and U.S.Pat. No. 4,784,993 of Lothar, et al. Further disclosures that are alsoincorporated herein by reference are: European Pat. No. EP0518900 B1 ofLonsdale; U.S. Pat. No. 5,585,571 of Lonsdale; PCT/GB97/03028 ofLonsdale; British Pat. Nos. 9902341-8 of Perry; 9909652.1 of Transense;9925873.3 of Transense; 99258736.3 of Transense; 9925538.2 of Lonsdale;GB9917579.6 of Transense; and 9915052.6 of Transense.

It would be advantageous if the antenna could also be embedded into thecomposite material of the wheel and wound around the hub of the wheelitself. A toroidal antenna, possibly helical in nature, may bepermanently incorporated into the wheel during manufacturing. Thepreferred antenna is described in U.S. Pat. No. 5,734,353 of VanVoorhles, et al.; U.S. Pat. No. 5,442,369 of Van Voorhles, et al.; andU.S. Pat. No. 5,654,723 of Van Voorhles, et al., and is incorporatedherein by reference as part of this work.

A particular benefit of this invention is that the sensor unit andcircuitry embedded into the composite wheel, is not limited to tiresensors only. A vast array of sensing devises can be incorporated intothe wheel that can communicate information about speed of the vehicle,footprint of the tire, accelerometers, breaking, steering, shockabsorption, weight dispersion per axle or per tire, and considerablymore information as can be relayed from tiny sensors that will interpretspecific information into RF signals that will be translated intoinformation transmitted to a monitor in the cockpit for the driver.

SUMMARY OF THE INVENTION

In accordance with the above advantages and objects, the presentinvention provides a new type of tire monitoring device for transmittinginformation about the tire pressure and temperature, among otherconditions to the operator of the vehicle. In a first embodiment, thereis at least a sensor including at least a wire free transmitter and areceiver for monitoring signals about the tire condition. Thetransmitter is used in conjunction with an antenna attached to orincorporated into the wheel rim for better operation conditions, and mayalso include a toroidal helically shaped antenna wrapped around theinterior of the wheel in the recessed portion of the wheel rim. Theantenna winding length may be from about 0.5 to about 5.0 meters long.

In another embodiment of the present invention, the wheel may be acomposite wheel made of a composite material selected from the groupconsisting of graphite, plastics, double skinned reinforcedfoam-centered plastic composites, aluminum alloys, Kevlar reinforcedplastics, and metal mesh reinforced plastics. The sensor can beincorporated into and embedded within the composite material, to becomea part of the wheel rim, with only the top of the sensor being exposedto the interior of the tubeless tire, so that it may monitor the tireconditions. The antenna, whether linear or toroidal, may also beembedded into the composite wheel so that it is permanently incorporatedinto the wheel. Then, the monitoring device is assured of remaining withthe vehicle, even though the tires may be removed, or if the wheel maybe rotated.

These and other advantages, objects and aspects of the present inventionare shown and illustrated in the accompanying drawings for the preferredembodiments and their modifications. A description of the preferredembodiments and the best mode of the present invention follows withreference to the drawings, in a manner so as to enable someone ofordinary skill in the art to practice the best mode of the invention, orits equivalents, without any undue experimentation on their part.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following drawings which illustrate various embodiments of thepresent invention:

FIG. 1 is a side elevational view of a vehicle wheel with a tiretemperature and/or pressure sensor having a wound around antenna inaccordance with the present invention;

FIG. 2 is a cutaway view of a section of FIG. 1 illustrating therelative positions of the sensor and antenna;

FIG. 3 a close-up sectional of an embedded sensor and an embeddedantenna in an embodiment of the present invention disclosing the use ofa composite vehicle wheel;

FIG. 4 is a top perspective view of a surface acoustical wavelength(SAW) transducer sensor useful in the present invention; and

FIG. 5 is a schematic diagram of a tire condition monitoring device inaccordance with the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the side of wheel rim having attached thereto the tiresensor and antenna configuration in accordance with the presentinvention. The entire tire sensing system is generally denoted bynumeral 10, including the wheel rim 12 having a wheel rim cavity 14 forreceiving the sensor housing 16 and the antenna attachment connector 18.Antenna 20 may be wound around the wheel rim, and acts to give a lengthywinding length of from about 0.5 to about 5 meters long. Antenna 20 maybe adhered to the wheel rim with adhesives, or it may be embedded into acomposite wheel. In the case of using a conventional steel wheel,antenna 20 may be a toroidal antenna having a diameter of from about 10millimeters to about 5 centimeters, as disclosed in U.S. Pat. Nos.5,734,353, 5,442,369 or 5,654,723, a winding length antenna, or anyother suitable antenna for use which will not interfere with radiofrequencies being emitted by cars which are located nearby. Wheel 12 maybe made of steel or may be made of new composite materials which areformed of plastics, and which may include composite materials ofgraphite, various plastics, double skinned reinforced foam-centeredplastic composites, aluminum alloys, Kevlor reinforced plastics, andmetal mesh reinforced plastics. Other suitable composite materials knownin the art may be utilized in the present invention.

Looking still at FIG. 1, it may be seen that one embodiment of thepresent invention includes a wound antenna attached to sensor housing 16by antenna connector 18. Winding antenna 20 may be wound around theinterior cavity of the wheel rim, and should be permanently attached,either with adhesives, or by embedding it into a coating on top of thesteel rim, or in the case of composite wheels, the antenna may beincorporated directly into the composite wheel.

Looking next to FIG. 2, which is taken along the cutaway lines 2—2 ofFIG. 1, there is shown how the sensor housing 16 and antenna 20 may beembedded directly into the wheel rim cavity 14. This is accomplishedduring the manufacture of the composite wheel by placing the componentsinto the mold and then introducing the plastic into the mold, therebyencapsulating and incorporating the sensor and the antenna directly intothe wheel.

In the manufacture of steel wheels, sensor 16 may be placed within acavity form in the steel wheel. The sensor (not shown in this figure) isheld within sensor housing 16. Preferably, the surface of sensor housing16 is open to the interior of the tubeless tire so that it may sensetire pressure and tire temperature. The sensor then will transmit andrelay information to a receiver which can either be mounted within thewheel or within the body of the vehicle, i.e. in the underbody and/orthe wheel well of the vehicle. The receiver may then be electricallywired and in electrical communication with a cockpit display which islocated in the interior of the vehicle on the dashboard, such that thedriver of the vehicle can view the information. Such cockpit displaysare conventional in the art, and one may be selected without undueexperimentation. The cockpit display may be a dashboard display in anautomotive vehicle. A cockpit communicator may also be included in thetire sensing system of the present invention, and it may act as anintermediary between the receiver and the cockpit display. Thecommunicator may be a microprocessor, or it may be a separate antennaand transmitter device. Although FIG. 2 illustrates antenna 20 beingpartial embedded, the present invention also envisions a completesubmersion of the antenna within the body of the composite wheel, suchthat antenna 20 would only appear below the surface of wheel rim 12.

FIG. 3 shows a closer view of the embedded sensor housing 16 withinwheel well 12. Antenna 20 is also shown partially embedded, although itmay be fully embedded with wheel rim 12. Wheel rim cavity 14 has thereinthe sensor housing 16 embedded within wheel rim 12. A sensor seat 24holds sensor 22 within place as well as sensor seat wall 26. Sensorhousing upper surface 28 is in contact with the air pressure of thetubeless tire through the cavity 14. The underside of the sensinghousing upper surface 30 is utilized to maintain the sensor 22 in itsproper place. Again, the sensor housing 16 may either be incorporatedright into the composite wheel while molding, or may be a separate piecewhich is inserted into the mold for receiving the sensor 22.

Looking next to FIG. 4, there is shown a sound acoustic wavelength (SAW)tire-sensing device in accordance with the present invention. The SAWsensor, generally denoted by numeral 32, includes interdigitaltransducers 34 adhered to the top of a piezoelectric substrate 36.Electrical output 38 is on one side of the device, while informationinput 40 is located on the other side. This SAW device is the preferredsensor to be used in the present invention, although many other sensorsmay be utilized, as described here and above in the background section.The sensor may be any standard sensor which is economical, and suitablefor registering and transmitting information about tire pressure andtire temperature. Of course, many other conditions may need to besensed, and applicable sensors for those conditions may be incorporatedtherein as well.

FIG. 5 shows a signal processing circuit in accordance with the presentinvention, which may have several functions. As shown, the SAW device 32may be in electrical communication with transmitter 42, either hardwired, or via antennas 60. A battery 44 is included which may beoperated by a centrifugal switch, not shown, which may also be includedto turn the system on or off when the vehicle is in motion, includingswitching off when the vehicle is stopped or switching into a sleep modeto extend the battery life. Within the SAW device, the tire monitoringsystem may include a temperature transducer and a pressure transducerwhich is shown above in FIG. 4. The receiver as generally denoted bynumeral 50, will receive signals from transmitter 42, eitherelectrically, or through radio waves, as are conventional in the art.The signals may be transmitted with wavelengths of between about 1 and150 Hz. The sensor notes changes in frequency from about 20 to 30 Hz,and will send a danger signal.

A conventional receiver, as shown, would include a band-pass filter 52,a preamp 54 and a decoder 56. This receiver would then be able to sendinformation signals to a cockpit display (not shown) or may be sent toan alarm 58 which would sound within the interior of the vehicle if oneof the conditions became so low that the vehicle should not be operated.The alarm may be visual or audible, depending on the desires of themanufacturer.

This entire tire sensor signal processor may be an analog to digitalconverter to convert the analog signals from the transducers to digitalsignals. Furthermore, more conventional means, including an all analogsystem, may be utilized. Typically, however, microprocessors are theleast expensive and most suitable means processing any digital outputsfrom the sensors to provide information regarding the temperaturepressure, or any of the other conditions which may be wanted to bemonitored including tire balancing, shock absorber condition, treadwear, wheel rotational speed, and other conditions which may be sensed.Changes in the wavelength transmitted may trigger the alarm to be setoff, or quantitive information may be relayed. Wavelength variationswill change with different tires and vehicles.

As discussed above, receiver 50 may be located on the wheel,incorporated into the material of the wheel itself, incorporated intothe underbody of the vehicle, or it may be located in or on the wheelwell itself. If the underbody of the car is made of composite materials,the receiver may be able to be molded directly into a portion of theunderbody. Furthermore, if the wheel wells are made by composites or dipmolding, or any other plastic forming technology, then incorporation ofthe receiver into the wheel well is achievable. Battery 44 is preferablya lithium battery, and would most suitably include a housing which isvirtually maintenance free. Battery life may be extended by the use ofthe centrifugal switch, in addition to the low voltage requirements ofmicroprocessors and the SAW device itself. Alarm 58 may signal a lowpressure or high temperature situation to the driver of the vehicle asdisclosed above.

INDUSTRIAL APPLICABILITY

This invention finds industrial applicability in the field of tirecondition and pressure monitoring systems for automotive vehicles,including cars and trucks. The present invention also finds industrialapplicability in the fields of agricultural, utility and recreationalvehicles, as well as in the aerospace industry.

1. A tire monitoring device for monitoring various tire conditions of atubeless tire mounted on a vehicle wheel rotatably mounted on an axle ofa vehicle, said vehicle having an underbody and wheel wells for housingthe vehicle wheel, said wheel having a recessed portion of the wheel anda wheel rim defining the recessed portion, said tire monitoring devicecomprising: a composite wheel having a recessed portion of the wheel anda wheel rim defining the recessed portion suitable for supporting atubeless tire mounted thereon, wherein said composite wheel is made froma material being selected from the group consisting of graphite,plastics, double skinned reinforced foam-center plastic composites,composite coated steel rim wheel, aluminum alloys, Kevlar reinforcedplastics and metal mesh reinforced plastics; at least a wire freetransmitter and a receiver for monitoring signals about the tirecondition having a wavelength of from about 1 to about 150 Hz; atoroidal antenna permanently incorporated into the recessed portion ofthe wheel rim, such that the antenna relays information about the tire,and wherein the antenna is embedded into the composite wheel such thatthe antenna is permanently incorporated into the wheel, not requiringany further assembly.
 2. The monitoring device of claim 1, wherein thetransmitter includes a surface acoustic wavelength sensor fortransmitting information about the tire pressure and temperature to theoperator of the vehicle.
 3. The monitoring device of claim 1, whereinthe receiver is located in a remote location from the vehicle wheelitself, where the receiver is in a location selected from the groupconsisting of the vehicle underbody and the vehicle wheel well.
 4. Themonitoring device of claim 1, wherein the toroidal antenna is from about10 millimeters to about 5 centimeters in diameter.
 5. The monitoringdevice of claim 1, further comprising a cockpit display.
 6. Themonitoring device of claim 1, further comprising a cockpit communicator.7. A tire monitoring device for monitoring various tire conditions of atubeless tire mounted on a vehicle wheel rotatably mounted on an axle ofa vehicle, said vehicle having an underbody and wheel wells for housingthe vehicle wheel, said wheel having a recessed portion of the wheel anda wheel rim defining the recessed portion, said tire monitoring devicecomprising: a composite wheel having a recessed portion of the wheel anda wheel rim defining the recessed portion suitable for supporting atubeless tire mounted thereon wherein said composite wheel is made froma material being selected from the group consisting of graphite,plastics, double skinned reinforced foam-center plastic composites,composite coated steel rim wheels, aluminum alloys, Kevlar reinforcedplastics and metal mesh reinforced plastics: at least one wire freetransmitter and a receiver incorporated into and embedded into thesurface of the composite wheel in the recessed portions of the wheelsuch that the transmitter and receiver are both permanently embeddedinto the composite wheel, and said transmitter and receiver are bothadapted for monitoring, transmitting and receiving signals about thetire condition, said transmitter transmitting signals having awavelength of from about 1 to about 150 Hz; an embedded antennapermanently incorporated into the recessed portion of the compositewheel, such that the antenna becomes a part of the wheel, with anantenna winding length of from about 0.5 to about 5.0 meters long. 8.The monitoring device of claim 7, wherein the at least one wirelesstransmitter transmits signals with information regarding the tirepressure and tire temperature to the operator of the vehicle.
 9. Themonitoring device of claim 7, wherein the receiver is attached remote tothe location of the wheel, in a location selected from the groupconsisting of the vehicle underbody and the wheel well.
 10. Themonitoring device of claim 7, further comprising a cockpit display. 11.The monitoring device of claim 7, further comprising a cockpitcommunicator.